The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
When treating bone fractures, where a single bone is broken into two or more bone segments, a medical professional often desires to promote union between the two or more bone segments. The same is the case when a medical professional desires to cause or help to cause bone fusions, i.e., uniting two bones into one bone by eliminating a joint therebetween. When promoting union of two or more bone segments via standard biologic healing, whether the bone segments are pieces of a single bone or whether the bone segments are separate bones, it is often desirable to have precise alignment of bone segments and complete or substantially complete contact between the involved surfaces.
Alignment of the bone segments is desirable not only to enhance a union of bone segments, but also to prevent or reduce the likelihood of subsequent deformity following union. If malalignment is created at the time of fracture fixation, the ability of the bones to heal may be compromised and, if union is achieved, an alteration in force distribution may occur across formerly precisely balanced joints that may lead to increased contact stresses and subsequent arthritis. Joints often require precise balance to prevent portions of the cartilage from accelerated wear (wearing away the cartilage with repetitive cycles of loading), which may lead to early onset arthritis.
Thus, under the above-mentioned circumstances, the ability of the medical professional to achieve an outcome that both the patient and clinician approve of is often directly related to the quality of the reduction of the bone segments.
Traditionally, medical professionals, such as orthopedic surgeons, use plate fixation to hold the various bone segments into the correct position while they heal. The plates themselves are typically primarily alignment devices. While they may provide some element of structural support, if the fracture or fusion does not heal (nonunion), the plate and screw construct often eventually fails due to cyclic loading.
Dynamic compression plates have been used by medical professionals to attempt to promote biologic healing by creating a more complete and flush bond between bone segments. One type of dynamic compression plate includes oblong, rather than circular, holes to allow the medical professional to compress the fracture/fusion site by placing the screw against the side of the hole that is farthest from the fracture/fusion site. This type of compression plate is utilized with fasteners, such as screws, having a cone-shaped head with its largest diameter at the top of the fastener head. As the medical professional tightens the screw against the plate, the screw head engages the far end of the plate screw hole. Then, as the medical professional continues to tighten the fastener, the cone-shaped fastener head pushes the plate in a direction away from the fracture/fusion site as long as two conditions are met: (1) the bottom side of the plate is in contact with the bone to prevent the plate from moving downward as the fastener moves downward, and (2) the other end of the plate is secured to the bone on the opposite side of the fracture/fusion site.
The first of the above-mentioned conditions, namely that the bottom side of the plate is in contact with the bone while the fastener is being driven downward into the bone, may diminish the plate's effectiveness or render the plate unusable with bones that are not relatively flat. For example, as the medical professional tightens a fastener and causes the plate to contact an uneven bone surface, the bone may become distorted or otherwise damaged. Distortion of the fracture or fusion site may alter the alignment of said site or may limit the contact surface area between the bone segments. In either case, the desired goal of anatomic restoration of the bone or fusion site with maximal surface area available for healing may not be achieved. As a result, this type of dynamic compression plate may be undesirable for use with curved or uneven bone surfaces.
This type of dynamic compression plate may also be undesirable because the amount of compression is dependent on the screw height. In other words, the position of the plate along a first axis is dependent on the position of the fastener along a second axis that is generally perpendicular to the first axis. The dependent relationship between the plate and the screw height may not be desirable because it may prevent the medical professional from creating a desired compression force acting on the bone segments while the fasteners are at their desired positions.
Therefore, it is desirous to provide an orthopedic plate, device, or method that can be used with bone segments having various shapes while allowing dynamic compression of multiple bone segments and/or that can be used to create a desired compression force acting on the bone segments while the fasteners are at their desired positions.